1. Field of the Invention
The present invention relates to an apparatus and method for sterilizing fluent materials while minimizing alteration of the natural flavor of the material and increasing the stability of these materials. The present invention is specifically directed to processing of a fluent product and, more specifically, milk and to a method where a major portion of the sterilizing medium is derived from the fluent product by evaporation, is condensed, reheated in a closed loop system and then reintroduced into a sterilizing chamber thereby isolating the fluent product from a source of possible contamination.
2. Background of the Invention
A number of processes and apparatus have been developed in recent years for the purpose of heat treating fluent material, such as a dairy product, to improve the shelf life of the product without adversely affecting the organoleptic properties of the food product or its nutritional value. Included in the parameters of primary concern to early workers in this field were the maintenance of aseptic conditions while guaranteeing the thoroughness of the sterilization process as well as control of the flow parameters so as to assure the effectiveness of the sterilization. For certain fluent food products such as milk, careful handling of the product throughout the processing is mandatory not only for health reasons but also for the preservation of the desirable taste and other organoleptic properties of the fluent food product. As a consequence, the expense of sterilization has been a prominent factor in the marketability of the treated product.
Representative of the prior art in this regard are U.S. Pat. Nos. 4,310,476, Reissue 32,695 and 4,591,463.
While the prior art has succeeded in providing effective and safe sterilization of the fluent food and other products discussed in the foregoing prior art patents, it has been difficult to maintain the cost of the product to the consumer on a level competitive with non-sterilized products of a comparable type. Also, the process of sterilizing with a medium foreign to the type of fluent product has created the misapprehension on the part of some consumers that the product could be adulterated by the sterilizing medium. This has been particularly true where the food product is milk since, as noted in the references, this product has shown significant sensitivity to sterilizing techniques as well as sensitivity in the market place to price variations of even a small amount. Accordingly, it has been apparent that improvements would be required in the manufacturing process and apparatus in order to enable a producer to place on the market a sterilized fluent product such as milk which is safe, of high, consistent quality and at a competitive price. It is to this end that the present invention is directed.